Knowledge base

Guides to the things worth understanding properly, with links to the live tools on Nollan.se.

• Electricity zones SE1–SE4 – why does the price differ?
  Why Sweden has four price zones and why the south often pays more.
• Summer time and winter time – when do we change the clocks?
  The dates, which way to turn them, and the EU debate about scrapping it.
• Public holidays and "squeeze days" in Sweden
  Fixed vs movable holidays, and what a klämdag really is.
• Northern lights in Sweden – when and where to see them
  The season, the best places and what the Kp-index tells you.
• Midnight sun and polar night in Sweden
  Where the Arctic Circle runs, and why the two are not equally long.
• How to see the space station from Sweden
  Why satellites only show at dusk, and how to tell one from an aircraft.
• Thunder and lightning: how far away did it strike?
  The three-second rule, and which safety advice actually holds up.
• What does "30 % chance of rain" actually mean?
  The most misread number in any forecast, and how far ahead they work.
• Leap years and 29 February
  The rule about 100 and 400, and the Swedish 30 February of 1712.

What this is

Nollan.se answers small everyday questions with a number: what week it is, when the sun sets, how many days until payday. A number is often enough. Sometimes it is not, and you want to know why the figure looks the way it does, or why it differs from what you expected.

That is what these guides are for. Each one takes a single question, explains the mechanism behind it properly, and stops there. They are written for this site rather than gathered from elsewhere, they are updated when the facts change, and every figure that comes from someone else's measurements names its source.

Who writes them and where the data comes from is set out under about Nollan.

The tools

Every guide pairs with a live page you can open any day:

• Name day today
• What week is it?
• Days until payday
• Sunrise & golden hour
• About Nollan